Provenance of the Red Sea Beach Sediments: Constraints From Zircon U‐Pb Geochronology and Sediment Geochemistry

ABSTRACT Young continental rift settings are premier sites for studying the dynamic interplay between sediment provenance and depositional setting. We integrated geochemical and detrital zircon U–Pb geochronology data of the Red Sea beach sediments to infer the weathering history and identify source terranes. Chemical composition with low Al 2 O 3 /TiO 2 ratios suggests an apparent mafic‐to‐intermediate provenance. Although internal variability exists, the chemical index of weathering (CIW) and Th, Sr, U and Ba contents reveal moderate weathering intensity in the source region. This interpretation is contradicted by our zircon U–Pb data, which uniformly fingerprint the felsic‐to‐intermediate Neoproterozoic (550–990 Ma) Arabian–Nubian Shield (ANS) as the single primary source. We resolve this paradox by demonstrating that robust coastal processes fundamentally overprint the primary source signature. Intense hydrodynamic sorting in heavy mineral placers removes light, felsic minerals, creating a residual deposit with an artificial ‘mafic’ signature and an artificially high CIW signal. Elsewhere, the detrital signal is masked by biogenic carbonate dilution. Furthermore, a subordinate suite of recycled Archean to Cretaceous zircons reveals cryptic contributions from the regional Nubian Sandstone Formation, tracking long‐term crustal inheritance. This work provides a case study of how depositional processes can mimic and mask source signatures in an active rift margin.